What gives some people the right to put others in prison? Is prison - and the criminal justice system generally - an ethically permissible method for dealing with criminality?

Individualist anarchist and prison abolitionist Jason Lee Byas goes over the common justifications for the prison system and explains why none of them succeed. Specifically, he covers the doctrines of retributivism (specifically desert retributivism and expressive retributivism), deterrence, rehabilitation, and rights forfeiture, arguing against each. In place of prison, Byas proposes a tort system of restitution. Monetary restitution may not be sufficient to right the wrong of a crime, says Byas; but it is all that the law should mandate, leaving other desired correction or compensation up to community-based initiatives (Byas cites restorative justice as an example of the sort of institutions that can take the place of those corrective aspects of criminal justice that retribution does not address). Byas also explains how a system of monetary restitution can get around problems of class-based inequality (for example, if someone is so rich that they don't mind having to pay to commit a crime, or if someone is so far in debt that another dent wouldn't matter). Finally, he explains how violent offenders who pose an "ongoing threat" might be handled in his preferred system.

For much of the 20th century, the Liar paradox has stood as an elusive and stubborn puzzle. The main solutions to it have significant drawbacks, such as blocking meaningful cases of self-reference or abandoning bivalence (the principle that all propositions are either true or false and not both). In recent decades, Stephen Read has rediscovered and defended a solution by the medieval thinker Thomas Bradwardine. If Bradwardine's argument is correct, the liar sentence is simply false. When properly examined, its falsity does not imply its truth. Bradwardine shows this with a clever argument that does not require us to abandon classical logic or block self-reference. It does rely on a controversial principle, "closure": any statement implicitly says (or means) everything that follows from what it says. Arguably, whether the Bradwardine solution succeeds or fails to conclusively solve the Liar depends on whether one accepts closure. In this interview, Stephen Read runs through Bradwardine's argument in some detail, then defends it against a few objections.

"This sentence is false". Is that sentence true or false? If it's true, then what it says must hold; but what it says is that it's false, so it must be false. But if it's false, then what it says must not hold; but what it says is that it's false, so it must not be false. But if it's not false, it must be true. So if the sentence is true, it is false, and if it is false, it is true. The sentence, therefore, seems to be both true and false, which seems absurd.

Philosopher and logician Stephen Read is one of the preeminent scholars on this "liar paradox". He is known, in large part, for rediscovering and defending a long forgotten solution to the paradox first proposed by the medieval philosopher Thomas Bradwardine. In this first half of our conversation, Read covers the paradox's rich and influential history. It was first discovered, in its full form, in the 4th century BCE by Eubulides (who also first set down the sorites paradox). It became a central problem in the 20th century via its association with Russell's Paradox, a major problem in the foundations of mathematics. Later in the century, two thinkers - Alfred Tarski and Saul Kripke - proposed monumentally influential theories of language and truth motivated, largely, by the paradox. But even after their contributions, the consensus is that the paradox remains unsolved. Quite a few new solutions have been suggested in the decades since Kripke's 1975 proposal. Among the more influential is Stephen Read's revival of the Bradwardine solution, which will the subject of part 2 of this interview.

We often think of religion as being centered around a series of beliefs. To be Christian, I must believe in the veracity of the Bible as a literal account of historical events. Doubt, then, is a problem to be dealt with. Understandable for a while, perhaps, but something which must be overcome in order to be in good standing with the faith.

T.K. Coleman offers an alternative approach to Christianity: a Sacramental approach, which focuses not on the belief requirement, but on the personal and transformative aspect of interacting with the Bible and with the faith. To be a Christian is not to have a set of beliefs, but to seek transformative experiences of intimacy with the divine. The literal truth of the Bible is, to an extent, secondary. Doubt becomes an inescapable part of interacting with the faith as a Sacrament. In the end, some stories may well be literally true, says Coleman; others best seen as metaphorical. For the second half of the interview, we discuss at length the metaphysical and epistemic issues surrounding belief in these stories, and in miracles broadly.

Mary has lived her entire life in a black and white room. In that room, she learned everything there is to know about the neurophysiology of perception. She knows everything that happens in the brain when a person sees a blue sky. One day, Mary leaves the black and white room and sees the blue sky. Has Mary learned something new?

Frank Jackson posed this famous thought experiment as a challenge to physicalists, such as David Papineau, who argue that qualitative experiences are identical to brain states. If this is really so, the argument goes, Mary isn't learning anything new, since she already knew everything about the relevant brain states. But she does seem to learn something new: what it's actually like to see blue. In this interview, Papineau addresses this challenge and explains why he thinks that, despite our intuitions to the contrary, qualitative experiences are simply neural states under a different description.

Most contemporary philosophers call themselves "naturalists" or "physicalists". But what do these labels really mean? What do they commit us to?

Philosopher David Papineau first puts it negatively: physicalists deny the existence of the supernatural, or of "anything spooky". More specifically, only those things that play a causal role in the spatiotemporal world exist. And, modern physics tells us, only the physical plays such a causal role. For this reason, "abstract objects" that don't themselves affect the physical world, such as numbers, should not be said to exist.

For much of the interview, Papineau runs through a "causal argument" to show that consciousness is physical. The argument begins with the premise that mental states have physical effects (for example, my experience of pain causes me to cry out). It also assumes that physical effects have only physical causes and that events aren't systematically overdetermined (caused by two things at once, like a man killed by a gunshot and a bolt of lightning at once). If this is all true, it follows that mental states must themselves be physical. Papineau runs through possible ways out of this causal argument, including epiphenomenalism. In the process, he runs through a brief history of modern physics and how we came to discover that all physical effects have physical causes. He concludes with an exploration of panpsychism and "Russellian monism", views that attempt to accept the causal argument but deny that consciousness is therefore strictly physical.

For some time, the answer to this perennial question was thought by many to be "justified true belief". If I believe X to be true, I have good reason for believing X to be true, and X really is true, then I know X. In 1963, Edmund Gettier published a now legendary three-page paper titled "Is Justified True Belief Knowledge?" in which he gave two examples of justified true belief that did not constitute knowledge. Since then, epistemologists have mostly agreed that there's some extra ingredient requisite for knowledge but have disagreed about what it is. After drawing out Gettier's examples, Peter Klein explains that there are two major camps. The first he calls etiology of belief: theories in which the extra ingredient has to do with how the belief was attained. Reliabilists, for example, argue that a justified true belief counts as knowledge if the belief is arrived at via a method that reliably delivers accurate beliefs. Klein belongs to the second camp: quality of evidence theories, which have to do with the strength of the justification, not the cause of the belief. Klein defends his own preferred quality of evidence theory: defeasibility theory, which involves the existence or absence of "defeaters" for the justification.

Suppose you know X. How do you know? Maybe you know because of Y. How do you know Y? Maybe the answer is Z. How do you know Z?

This is the regress problem of knowledge, also called the Agrippan trilemma and the Münchhausen trilemma. It is based on the supposition that if we claim to know something, we must have a reason for it and that reason must itself be something that we know. This leaves open four possible solutions. One is skepticism, the belief that we have no knowledge. The most common is foundationalism, which posits certain basic facts that require no external reasons to be justified. Another option is coherentism, which solves the problem via a kind of circular reasoning or justification loop. And finally, there is infinitism, the view that there is no end to the regress. For any chain of justification, the final member of the chain will always be unjustified, and it is always possible to go looking for further reasons of reasons of reasons. As infinitist Peter Klein puts it, knowledge is never "settled". Even so, says Klein, it is still possible to have knowledge. In this interview, Klein first argues why he thinks coherentism, foundationalism, and a certain kind ofskepticism all fail. He then explains his own account of justification, as "something that we do", and how it makes the infinitist picture look more plausible than it first seems. Along the way, he recounts the framing of the problem by Sextus Empiricus in his book Outline of Pyrrhonism. Klein argues that the ancient Greek Pyrrhonians, though they called themselves skeptics, were really infinitists.

Economist Bryan Caplan breaks down the law into three components: rule formation, arbitration, and enforcement. For all three, he provides examples of how these are already provided without the state in many contexts. He also explains the theoretical reasons we shouldn't be surprised to find law provided without the state, usually better than the state does. He goes on to speculate how the law could be provided if there were no state at all. Finally, he considers two common objections: that law without the state leads to chaos, and that providers of legal services in a world without the state will inevitably collude and come together to form a new state.

Why do students go to school? The usual answer is to learn. But if this is true, why do students rejoice at canceled class? Why do they prefer an easy "A" instructor over a difficult one who has more to offer? Why don't they just sit in on classes for free, which you can do at many of the best schools? And why is the final year of school so much more lucrative than other years, given that we don't usually learn more that year?

These problems and others fall into place when we consider that we go to school more for the degree than for the education. The main purpose of education is to send a signal to employers, says economist Bryan Caplan. Employers pay more for college-educated employees not because what they learned in school was itself useful, but because the fact that they got the degree demonstrates that they must be generally smart, disciplined, and conformist. This makes little difference to the individual - you should still go to school and send that signal. But for society, this makes education a bad deal; status, unlike learning, is zero-sum, making much of the education system a waste of resources. In this interview, Caplan explains the signaling model in more detail, addresses objections, and predicts what would happen if his prescriptions were followed.